1. Field of the Invention
The present invention relates to a method and an apparatus for controlling a fuel injection for a diesel engine. The method and apparatus according to the present invention are applied to a diesel engine utilizing a pilot injection process.
2. Description of the Related Art
As is well known, a loud engine noise occurs when the diesel engine is idling. This engine noise is caused by combustion and is called "idling knocking". In a conventional technique for eliminating this engine noise, making a pilot injection before a main injection is considered an effective way of preventing this "idling knocking". Although the pilot injection quantity and a non-injection period before the main injection have been improved and optimized, it has been found that the optimal pilot injection quantity and the optimal non-injection period vary in accordance with the Cetane number of a fuel and a temperature of an engine cooling water.
It is very difficult to control these parameters, particularly the Cetane number of the fuel, and accordingly, a satisfactory fuel injection control method and apparatus have not been proposed as yet.